Alternating-current meter on ferraris principle.



PAIENTED MAY 1 .E. MORGK. :ALTBRNATING CURRENT METER ON PERRARIS PRINOIPLE.

APPLICATION FILE D MAY 10, 1904- IIIIIIII E'IIIIIIIIII PATENT orrioiif EMANUEL M o 'o K; or FRANKFoRr-oN T E MAIN, GERMANY-lag LTERNATiNG-ouR EN -r.METER' N' F EBRARlS PRJINICIPLE."

To all whom it. may concern/k f Be it known that nm m-Mogm,

' electrical engineer, a subject of theGerman Emperor,

German Empire, have invented a certain new and useful Improvement in Alternating-Current Meters on Ferraris Principle; and I do hereby declare the following to be a lull, clear, and exact description of the invention, such as will enable others skilled in the art to. which it in which Ep. J. cos. 1;) represents the wo k appertains to make and use the same, refer-5 encebeing had to the accompanying draw ings, and to letters of reference marked there on, whichform a part of this specification.

"My invention relates to an alternatingcurrent me teron Ferraris principle. The number of revolutions of the armature is done by the alternating current." .c is he damping by the permanent magnet. 0, Ep. is the damping by the'potential coil. 0 J 2 is thedamping by'thecurrent-coil. Thisequation (1) is correct in cases where the friction j is accurately com ensated for, the frequency is constant, and t e acting fields are proportional to E .and J. If-now Ep. and cos. p be I P constant, t

en the equation (.1) assumes the form J. a i Y wear .(2')

If be varied, then ail should vary in the same proportion in order that the meter may onsumption inwatts; but this is not the case, because, as is shown by the equation (2), the numerator of the fraction increases linearly, as J, so that conregister the exact sequently the denominator ought to be constant yet the. denominator increases, and, in

fact, increases as the sqpare of J in the second member of the sum 't at is tosay, the ratio or proportional number. between the number of revolutions of the armatureandthe consumption in watts diminishes as J increases. -Attempts have-been made to ob- "viate this decrease by distorting the currentfield or by causing "an auxiliary coil dependent on the main current to act together with the main-current coil of the-motor, so as to produce an additional torque or turning mo- Specification of Letters Eatent. Application filed May 10, 1904. Serial liq. 207,315.

menty proportional to 1J and a' resident of33 Ulmenstrasse,

-' j 15; Frankfort onthe -Main,

nearly as possible as'JF.

elevation and in plan.

atenteo May 1, 1906. i

In such a case *doesnot contain any real constant, bepause From this it is clear that such a numerator the factor of J in the equation (3) 'isnot a .1 constant number.

Nowthis invention has for its'object to proyiding an additional torque or turning 'produce'a real constant for the numerator by moment which "shall increase as J or as i then assumes the form a.J+ bJ stant fon all current quantities or"strengths The equation (3) Thefactor of J in the equation (4) is con L where the proportions or circumstances are pendent on the main current, to act upon the armature, said auxiliary coil having as far as Figures 1 and 2 of the accompanying-diagrammatic drawings show one construction of apparatus according to this invention in the auxiliary .coil containing iron. This lat which can be done without ,ossible a quadratic curve of magnetization. Q

a is-the' armature; 1), the potential, coil; 0, the main-current coil; d,

ter coil should have as far as possible a quadratio curve of magnetization. .Fig'. 3 is a diagram-showlng a curve of; magnetization of this kind for a determined sort of iron,while the inscribed points belong to a quadratic curve.

The coil d acts together with the coil 0 u on the armature, and the only condition is t at thereshould be a difference of phase between the fields of the two coils. The-suitable con-. formation of the coil (1 and also the regulation of the amount of the additional torque or turning moment for a determined 'J may be efiected in many ways. i

For the following reasons the magnetism increases as the third power of the current.

The main-current coil produces a field that is i As will be seen there is almost complete coin- 1 vcidence or agreement up to 13 9,000,

proportional to the current. The auxiliary coil produces a field that increases as the second power of the current. The main coil and the'auxiliary coil impart to the armature a turning moment that is pro ortional to the product of their fields, and t e said product increases as the third power of the current. Thus the two coils produce together a turning moment that increases as the third power of the current.

The reason for the increase of the effect of the auxiliary 'coil as the second 1power of the or the auxiliary coil.

current is as follows The tota flux in the core of the auxiliary coil increases more thanproportional to'the current J within the range of the apparatus. The iron is thus little saturated over the entire range. Thebridge, however; is slightly saturated when I the current is small, and it is highly saturated when the current is high. Consequently when the flux is divided into a flux through the armature and a flux through the brid e, a relatively small flux passes through 51c armature anda great flux ,throu h the bridge when the current is weak.

pass through the bridge and relatively many pass through the armature. The the iron and air cross-sections of t e paths of the iron and air lines of forceare selected in such a'manner that the field of the auxiliarycoil passing through the armature increases as the second ower of the current J. It will thus be seen that only the rapidly-increasing portion of the curve of'magnetization is used The said portion of the curve is, as will be seen from Fig. 3, very much like the quadratic curve. In Fig. 3 is,

for the sake of com arison, indicated a quadratic curve, for which follows the law y= (3.6 so)". 1 The curve in full line thus repre-' sents the curve of ma netization (as found by experiments) fora (Ietermined sort'of iron by slight vsaturationthat is to say, the curve indicates the law governing the increase of B with H. The small circles relate v to the curve y: (3.6 m)

It will easily be seen from Fig. 3 that up to B 9,000 the experimentally-found curve of .magnetization is very much like the quaden the our rent is stronger, relatively less lines of force ortions of poles of the coils in which t -mature of the auxiliary coi ratic curve y 3.6 at)? It thus follows that within the limits shown in Fig. 3 the induction B of the auxiliary coil increases, when the said sort of iron is used, as the second power, while H increases linearly.

As H is proportional to the current J, the

field of the auxiliary coil consequently increases asthe second power of J when J increases linearly, and t e turning moment of both coils, therefore, increases as the .third' power ofJ, when J increases linearly.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States of America, 1s

1. In an alternating-current.meter on Ferraris principle, means providing an additional torque or turning moment on the armature which additional torque or turning moment increases exactly'as or as far as is possible approximately as the third power of the effective current, for the pur ose of eliminating the variable damping in uence of the current-coil upon ,the indications of the meter, substantially as set forth.

2. In an alternating-current meter of Ferraris principle, the'combination'of the mainiron, dependent on the main current and. havmg approximately a quadratic curve of magnetization as. long as the iron remains unsaturated by the current in question, substan- HENRY HASPER, KARL FRANCKE.

current coil with an auxiliary coil containing 

